Most adults need 7 to 9 hours of sleep per night. The sweet spot for longevity and lowest disease risk, based on large-scale population studies, sits right around 7 hours. But your ideal number depends on your age, activity level, and individual biology.
Recommended Sleep by Age
A panel of sleep experts reviewed over 300 studies to establish the current guidelines published in the journal Sleep Health. The ranges reflect genuine biological differences in how much sleep the brain and body need at each stage of life:
- Newborns (0 to 3 months): 14 to 17 hours
- Infants (4 to 11 months): 12 to 15 hours
- Toddlers (1 to 2 years): 11 to 14 hours
- Preschoolers (3 to 5 years): 10 to 13 hours
- School-age children (6 to 13 years): 9 to 11 hours
- Teenagers (14 to 17 years): 8 to 10 hours
- Young adults and adults (18 to 64 years): 7 to 9 hours
- Older adults (65 and up): 7 to 8 hours
These are ranges, not targets. Someone who functions well and feels rested at 7 hours doesn’t need to force themselves to sleep 9. The range exists because people genuinely differ.
Why 7 Hours Keeps Showing Up in Research
A major meta-analysis in the Journal of the American Heart Association looked at the relationship between sleep duration and risk of death, heart disease, and stroke across dozens of studies. The pattern was a clear U-shape: both too little and too much sleep raised health risks. The lowest risk for every outcome examined landed at roughly 7 hours per night, with little variation between men and women.
That doesn’t mean 8 hours is dangerous. It means that if you consistently sleep 5 or 6 hours and think you’re fine, the data suggests your body is paying a price you may not feel day to day. And if you regularly sleep 10 or more hours, that pattern is also linked to higher health risks, though it’s harder to say whether the long sleep causes problems or simply signals an underlying condition.
How Sleep Cycles Affect Your Number
Your brain cycles through light sleep, deep sleep, and REM sleep roughly every 80 to 100 minutes. Most people complete four to six of these cycles per night. Deep sleep dominates the earlier cycles, while REM sleep (when most vivid dreaming happens) increases toward morning.
This is why waking up at the wrong moment can leave you groggy even after plenty of sleep. If your alarm catches you in the middle of deep sleep, you’ll feel worse than if you’d woken naturally at the end of a cycle. Counting backward from your wake-up time in roughly 90-minute blocks can help you choose a bedtime that aligns with your natural cycles. For example, if you need to wake at 6:30 a.m., falling asleep around 11:00 p.m. gives you five full cycles, or about 7.5 hours.
Signs You’re Not Getting Enough
The Epworth Sleepiness Scale, a tool used by sleep clinics, asks you to rate how likely you are to doze off in everyday situations like reading, watching TV, or sitting in traffic. A score of 10 or higher suggests your current sleep duration isn’t meeting your biological needs. But you don’t need a formal score to notice the warning signs: relying on caffeine to get through the afternoon, falling asleep within minutes of lying down, or struggling to concentrate during routine tasks all point to a sleep deficit.
Cognitive testing makes the cost of short sleep very concrete. When healthy adults spent 14 consecutive days sleeping just 6 hours a night, their error rate on a reaction-time task increased by 177% compared to those sleeping 8 hours. Even modest restriction to 7 hours slowed response times by 12%. The insidious part is that people in these studies consistently underestimate how impaired they’ve become.
Athletes and Physically Active People
If you exercise intensely or train for a sport, you likely need more sleep than the general recommendation. A study of elite athletes found they needed an average of 8.3 hours to feel rested. About 80% reported needing between 7 and 9 hours, which lines up with standard adult guidelines, but the average skewed toward the higher end of that range.
Sleep is when your body does its heaviest repair work on muscle tissue, consolidates motor skills, and restores the mental sharpness needed for fast decision-making. Cutting it short doesn’t just make you tired. It reduces time to fatigue during repeated bouts of exercise and increases decision-making errors in sports played over extended periods.
Sleep Needs During Pregnancy
Pregnancy shifts sleep needs and makes getting enough sleep harder at the same time. In the first trimester, a spike in progesterone can make you feel unusually drowsy. The second trimester often brings some relief. By the third trimester, finding a comfortable position becomes difficult, and rising estrogen levels can cause nasal swelling that leads to snoring or sleep apnea.
Getting fewer than 6 hours of sleep during pregnancy is linked to higher rates of preeclampsia, gestational diabetes, longer labors, and cesarean delivery. The body is doing enormous biological work during pregnancy, and sleep is when much of that work happens.
How Sleep Changes After 65
Older adults still need 7 to 8 hours, but the architecture of their sleep changes in ways that make hitting that number harder. Deep sleep, the most physically restorative stage, begins declining in early adulthood and drops substantially by the time you’re in your 60s and 70s. Elderly adults have shorter periods of deep sleep and fewer of them.
The result is that older adults often can’t get all the sleep they need in a single unbroken block. Waking in the middle of the night becomes more common, and total nighttime sleep may fall short. A brief daytime nap can help make up the difference without disrupting the next night’s sleep, as long as it stays short.
Do Naps Count Toward Your Total?
Yes, naps contribute to your overall daily sleep, but they work best as a supplement rather than a replacement. A 15- to 20-minute nap can boost alertness for a couple of hours afterward and causes minimal grogginess because you haven’t entered deep sleep yet. It also won’t reduce your sleep drive enough to keep you up at night.
Longer naps are trickier. If you wake up after about an hour, you’re likely pulling yourself out of deep sleep, which can leave you feeling significantly worse than before the nap. If you have the time and need a longer rest, aiming for about 90 minutes lets you complete a full sleep cycle and wake during a lighter stage, reducing that heavy, disoriented feeling.
Weekend Catch-Up Sleep Doesn’t Work
If you sleep 5 hours on weeknights and try to make it up on Saturday and Sunday, you’re not actually erasing the damage. A controlled study at the University of Colorado tracked three groups over two weeks: one group slept 9 hours a night, one slept only 5, and a third mimicked the common pattern of 5 hours on weekdays with weekend sleep-ins.
The results were striking. The sleep-deprived group gained about 3 pounds and experienced a 13% drop in insulin sensitivity (a marker for diabetes risk). The weekend catch-up group fared even worse on some measures, with a 27% drop in insulin sensitivity. Their liver and muscle tissue showed metabolic changes that didn’t appear in the group that was simply sleep-deprived all the time. Sleeping in on weekends gave people the feeling of recovery without the metabolic reality of it.
Finding Your Personal Number
The best way to find your ideal sleep duration is a simple experiment. Pick a week when you don’t have early obligations. Go to bed when you feel tired and wake up without an alarm. After a few days (the first couple may involve extra sleep as you clear any existing debt), you’ll settle into a consistent pattern. That natural duration is your baseline need.
Most people land between 7 and 8.5 hours. A small number of people carry a genetic trait that allows them to function well on 6 hours or less, but this is genuinely rare. If you think you’re one of them, consider whether you’re actually thriving on short sleep or simply accustomed to functioning while impaired. The cognitive studies suggest most people who believe they’ve adapted to short sleep have actually just lost the ability to notice how much it’s costing them.